/* AI 学习社区 - 页脚美化 */
#ft {
    background: linear-gradient(180deg, rgba(10,14,26,0.95) 0%, rgba(5,8,18,0.98) 100%);
    border-top: 1px solid rgba(0,212,255,0.15);
    margin-top: 40px;
    padding: 40px 0 20px;
    position: relative;
}
#ft::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 2px;
    background: linear-gradient(90deg, transparent, #00d4ff, #a855f7, transparent);
}
.ft_columns {
    display: grid;
    grid-template-columns: 1.5fr 1fr 1fr 1fr;
    gap: 30px;
    margin-bottom: 30px;
}
.ft_col {
    margin: 0;
}
.ft_col dt {
    font-size: 16px;
    font-weight: 700;
    color: #e0ecff;
    margin-bottom: 16px;
    padding-bottom: 10px;
    border-bottom: 2px solid rgba(0,212,255,0.2);
    position: relative;
}
.ft_col dt::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 40px;
    height: 2px;
    background: linear-gradient(90deg, #00d4ff, #a855f7);
}
.ft_col dd {
    margin: 0;
    padding: 6px 0;
}
.ft_col dd a {
    color: #8fa3bf;
    text-decoration: none;
    font-size: 14px;
    transition: all 0.2s;
    display: inline-block;
}
.ft_col dd a:hover {
    color: #00d4ff;
    transform: translateX(4px);
}
.ft_desc {
    color: #6b7f99 !important;
    font-size: 13px !important;
    line-height: 1.8 !important;
    transform: none !important;
}
.ft_desc:hover {
    transform: none !important;
    color: #6b7f99 !important;
}

/* 下拉菜单样式 */
.ft_dropdown {
    position: relative;
}
.ft_dropdown > dt {
    cursor: pointer;
    user-select: none;
}
.ft_dropdown > dt::before {
    content: '\25BE';
    float: right;
    font-size: 12px;
    color: #00d4ff;
    transition: transform 0.3s;
}
.ft_dropdown:hover > dt::before {
    transform: rotate(180deg);
}
.ft_dropdown .ft_dropdown_menu {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.35s ease, opacity 0.3s;
    opacity: 0;
}
.ft_dropdown:hover .ft_dropdown_menu {
    max-height: 300px;
    opacity: 1;
}
.ft_dropdown .ft_dropdown_menu dd {
    padding: 8px 12px;
    border-radius: 6px;
    transition: background 0.2s;
}
.ft_dropdown .ft_dropdown_menu dd:hover {
    background: rgba(0,212,255,0.08);
}

/* 底部版权 */
#flk {
    float: none !important;
    text-align: center;
    padding-top: 20px;
    border-top: 1px solid rgba(0,212,255,0.1);
}
#flk p {
    color: #5a6f8a;
    font-size: 13px;
    margin: 5px 0;
}
#flk a {
    color: #00d4ff;
    text-decoration: none;
}
#flk a:hover {
    color: #a855f7;
}
#flk .pipe {
    color: rgba(0,212,255,0.2);
    margin: 0 8px;
}
#frt {
    text-align: center;
    margin-top: 10px;
}
#frt p {
    color: #4a5f7a;
    font-size: 12px;
}
#frt a {
    color: #6b7f99;
    text-decoration: none;
}
.xs0 {
    color: #4a5f7a !important;
}

/* 响应式 */
@media(max-width: 768px) {
    .ft_columns {
        grid-template-columns: 1fr 1fr;
        gap: 20px;
    }
    .ft_dropdown .ft_dropdown_menu {
        max-height: none;
        opacity: 1;
    }
}
@media(max-width: 480px) {
    .ft_columns {
        grid-template-columns: 1fr;
    }
}